• Energy Research

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This paper presents the Life Cycle Assessment (LCA) of a glycerine production process as one of the most energy-intensive chemical processes. The utilisation of biomass as a solution to replace the current fossil fuels in the process is proposed. To do so, different energy mix scenarios are defined to moderate the impacts of glycerine production and utility generation during the energy transition period. In this research, the implementation of LCA in conjunction with Cumulative Exergy Demand to evaluate the sustainability of the developed energy mix is proposed. This LCA study confirms without retrofitting the core of the glycerine process technology, it is possible to reduce the environmental impacts through the step-wise introduction of biomass into the energy mix, resulting in four different scenarios. This study also confirms that, according to the discernibility analysis through Monte Carlo simulations, LCA results are responsive and sensitive to the portion of biomass in each energy mix scenario. Moreover, this study shows that the overall anthropogenic environmental impacts of the glycerine production process are reduced (41% according to Cumulative Exergy Demand) through natural gas to biomass energy transition. However, the biomass-based scenarios are less sustainable than the natural gas scenarios regarding photochemical oxidant formation.

Polyol ether production process can result in emission of extremely hazardous substances besides it requires high energy demand which can also cause environmental impacts. This paper presents an exergy-aided life cycle assessment (LCA) to pinpoint avoidable key causes of the environmental unsustainability in the period of clean energy transition, and enhance the sustainability as much as achievable. The power generation system is pinpointed as the mitigable key source of the unsustainability of the polyol ether production under the strict process constraints imposed by the energy transition. Then, a set of possible scenarios supported by Monte Carlo simulations are defined, resulting in reducing environmental impacts from 7.17 to 7.11 MJ equivalent of nonrenewable energy sources according to the Cumulative Exergy Demand or from the dimensionless normalized results of 3.43E-04 to 2.98E-04 according to ReCiPe. Moreover, LCA is advantageous to quantify precisely environmental impacts of each chemical component, showing that CO2 has much more adverse impacts on human health than the hazardous substances. Additionally, LCA reveals that natural gas can even be less sustainable than residual fuel oil in terms of freshwater ecotoxicity (75%), marine ecotoxicity (51%), terrestrial acidification (27%), human toxicity (43%), particulate matter formation (18%), and fossil depletion (64%) impacts. (C) 2017 Elsevier Ltd. All rights reserved.

Abstract Estimation of cogeneration potential prior to the design of the total site utility system is vital to set targets on site fuel demand and steam flowrate as well as heat and power production. This paper presents in detail the Iterative Bottom-to-Top Model (IBTM) as a new shaftwork targeting model which facilitates the targeting stage. The IBTM calculates the temperature of steam mains, steam flowrate and shaft power generated by the steam turbines in expansion zones of the site utility grand composite curve from bottom to top using a simple steam turbine expansion model with a constant isentropic efficiency. Unlike the existing models, IBTM provides the degree of superheat at process steam generators and steam boiler house. Through a case study of a refinery plant, the applicability of the IBTM in total site analysis is presented. It has been shown that the features of IBTM make it preferable for its implementation in flexible targeting tools to set realistic targets on the site fuel demand and the cogeneration at the early stages of design.

This paper presents a case study on the enhancement of environmental sustainability in a petroleum refining process based on an exergetic diagnostic approach. The Life Cycle Assessment (LCA) pinpointed crude oil production and electricity generating systems as the main sources of environmental unsustainability. The existing hot utility demand of the process is 78.4 MW with a temperature difference of 40°C, where the area efficiency of the existing design is 0.7254. The targeting stage sets the minimum approach temperature at 18.96 °C, thereby establishing the scope for potential energy savings. The suggested design option with a total energy demand of 109,048 kW, the same as the existing one but 72,699 kW higher than the target, needs a 17,873 m2 area in 38 exchangers. Notably, this requires 2,914 m2 less surface area, suggesting the practicality of the project with a limited number of modifications such as the repiping of the existing exchanger units. Moreover, to enhance further the sustainability of the petroleum refining process, the possible solutions such as the renewables were evaluated through various scenarios; thus, resulting in a reduction in the environmental impacts from 2.34E-06 to 2.27E-06 according to ReCiPe, and thus paving the way towards a sustainable petroleum refining process.

AbstractDeveloping material flow models of waste and recycling streams can be crucial to determining the inefficiencies of post-consumer plastic packaging recycling systems. Currently, there is no such material flow model of beverage carton packaging waste in The Netherlands because beverage carton management is inherently difficult to measure and calculate. This paper presents a material flow model of beverage carton packaging waste in The Netherlands by calculating potential, collected, sorted, and recycled beverage carton dry weight. The results show that of a potential 60,000 tons of beverage carton material, 47,124 tons are recycled while 12,876 tons end up incinerated. This quantification does not only serve as a starting point for additional research and environmental policy considerations to improve the sustainability of the post-consumer plastic packaging recycling system, but it can also contribute to research in similar settings, leading to a more complete overview of the municipal solid waste recycling system. Graphical abstract

The purified terephthalic and isophthalic acids production process was improved through the exergy analysis approach demonstrated in this work. The overall exergy losses and low-exergy-efficient units were first identified and presented using visualised exergetic flowsheets. Recommendations were then proposed to reduce losses based on the main cause(s) of irreversibility. Three out of the five constituent blocks contained the highest exergy losses. The oxidation block was the main player where it was suggested that using several reactors in series with gradually decreasing temperatures could lower losses. The product refining block had the second-largest irreversibilities, where improving coolers' performances were recommended. The crude terephthalic acid crystallisation block was the third-largest loss producer, where isothermal and isobaric mixing in the solvent dehydrator was suggested to reduce losses. The approach used in this work can be adapted to improve the energy footprint of other chemical processes.

AbstractBiobased products can achieve carbon negativity by storing biogenic carbon in the technosphere through circular loops. Quantifying these benefits requires quantitative assessment tools such as life cycle assessment (LCA). However, the LCA of biobased materials is not straightforward due to the complexity of addressing agroecosystem carbon dynamics and the timing of emissions. The aim of this research is to apply the novel framework of biobased materials and products‐life cycle assessment (BBM‐LCA) to the example of polylactic acid (PLA) to show how it can address biogenic carbon and timing issues of emissions by combining net ecosystem exchange (NEE) and dynamic LCA. BBM‐LCA adapts two aspects of conventional LCA to estimate the climate impact of biobased products more accurately. First, concerning the absorption of atmospheric carbon during cultivation, BBM‐LCA uses NEE to account for all biogenic emissions occurring within the agricultural ecosystem. This means that it is not limited to the absorption of carbon by agricultural crops. Second, concerning the calculation of climate impacts, BBM‐LCA adopts dynamic LCA as a time‐dependent approach, to generate a time‐sensitive global warming potential (GWP). The example of PLA proves that BBM‐LCA is an effective instrument for calculating the climate impact of biobased products due to the implementation of a holistic lifecycle approach and a dynamic impact calculation method. BBM‐LCA accounts for the carbon sequestration benefits of recycling, recognizing its actual impact over time in multiple lifecycles. This feature makes BBM‐LCA preferable over conventional LCA, which struggles to track greenhouse gas (GHG) emissions at different points over multiple years across the multiple lifecycles of recycled products.

Chlorine production process can result in discharge of tremendously harmful materials besides it requires high‐energy need, which basically can also lead to additional environmental impacts. This article presents an exergy‐aided life cycle assessment (LCA) to evaluate power generation from natural gas and biomass in the phase of green energy transition to augment the sustainability as much as attainable. A series of statistically discernible scenarios assisted by Monte Carlo Simulation are specified. Results show a reduction in environmental impacts from 2.249E‐02 to 2.180E‐02 MJ‐Eq of nonrenewable energy supplies in accordance with the cumulative exergy demand or from 1.28E‐06 to 7.62E‐07 in accordance with ReCiPe 2008, paving the way toward an environmentally sustainable chlorine production process. LCA is useful to measure the environmental impacts of each chemical constituent accurately, showing that CO2 emitted from this process has much more unfavorable impacts than other harmful materials on human health. Furthermore, LCA discloses that the natural gas could even be less environmentally sustainable than residual fuel oil concerning human toxicity freshwater ecotoxicity, marine ecotoxicity, particulate matter formation, terrestrial acidification, and fossil depletion impacts. © 2019 American Institute of Chemical Engineers Environ Prog, 38:e13146, 2019